Customizable Pegboard Things

This is a small collection of customizable pegboard things:
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* An adapter with hooks for aligning a pegboard to shelf standards
* Combination spacer/support for supporting the pegboard from the bottom
* A pegboard tray for holding loose stuff
* Pegboard hooks
* Straps for attaching a Tenergy TB6B battery charger to a pegboard
* Pegboard 1S LiPo 6in1 charger holder
* Pegboard anchor hook and nub module used by the other pegboard modules

Update jul-2022:
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* Moved pegboard-1s-6in1-charger-holder customizer parameters from
pegboard-1s-6in1-charger-holder.scad to pegboard-things.scad. Refactored
pegboard-1s-6in1-charger-holder.scad modules to take input parameters.
* Added utility .scad file duplicate-shapes.scad.

Update mar-2022:
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* The pegboard things OpenSCAD files have gone through a fairly major restructuring in order to consolidate common parameters and customizabl